Laurence Harvey wears a Rolex Submariner

On the morning of 19 April 1956, Lionel Crabb slipped into Portsmouth Harbour to examine the hull of a visiting Soviet cruiser and never came back up. He had checked into the Sally Port Hotel two days earlier with a companion registered as Matthew Smith. Fourteen months later a body in a diving suit surfaced near Pilsey Island in Chichester Harbour, missing its head and both hands; a wartime colleague identified it by a scar on the left knee, and the coroner never determined how he died. The Silent Enemy (1958) arrived in the middle of that mystery. William Fairchild filmed Marshall Pugh's biography of Crabb as a Second World War story, with Laurence Harvey playing the frogman in his Gibraltar years, and the picture carries a dedication to the frogmen of all nations and to the memory of Commander Crabb.

On screen, Crabb clears Italian limpet mines from Allied hulls in Gibraltar and works against the frogmen operating from the interned tanker Olterra. The film gives him a climactic raid that destroys the Olterra, which never happened, and a quieter moment with a basis in his character, the respectful burial of two Italian divers. On his wrist through the diving scenes sits a Rolex Submariner, reference 6538, the Big Crown, and near the end the film holds it in a dripping super close-up: ROLEX legible on the black dial, the oversized crown bare of guards, water beading on the bracelet. That watch did not exist in the 1940s, when the real events took place.

The film's watch record was assembled decades later, frame by frame, by vintage Rolex researchers working partly from stills a Belgian reader sent in. Among movies with a Submariner on screen, only a 1954 documentary is known to be older.